Method of reconditioning drill pipe



June 19, 1945. w. A. ABEGG METHOD OF RECONDITIONING DRILL PIPE Filed July 15, 1943 INVENTOR. 7m)" 4 417699, By fi A TTORNEY Patented June 19, 1945 METHOD OF RECONDITIONING DRILL PIPE Walter A. Abegg, Los Angeles,-Calif.,. assignor to Abegg & Reinhold Co. Ltd., Los-Angeles, CaliL, a corporation of California Application July 13,1943, Serial No. 494,557

2 Claims.

Thepresent invention relates generally to what is commonly known in connection with the drilling of oil wells by the rotary method, as the reconditioning of drill pipe, by which it is sought to restore worn drill pipe lengths or stands to effectively usable condition without replacement of parts. Efllciency in reconditioning, with economy, constitute the primary purposes of reconditioning methods and apparatus now in use.

Drill pipe, as employed in lengths or stands at present, is costly, as are the collar members at opposite ends of the pipe stands, either integrally upset thereon or substantially permanently connected thereto, which form the tool joints between the stands. One such collar member at the upper end of a stand of pipe carries an internally threaded upper or outer end portion or box, and the other member, at the lower end of the stand, carries an axially, downwardly projecting externally threaded portion or pin. The pins and boxes have mating threads, known as tool joint threads, so that the stands may be quickly and efilciently connected and disconnected at the tool joints, going into and out of the hole incident to change of the drilling bit and other necessary well operations.

The above mentioned collar members, forming the tool joints, are of substantially greater outside diameter than the drill pipe and hence, in the high speed rotary drilling of the present day, whipping of the drill string in the hole almost continually forces abrasive contact of the collars with the wall of the hole, so that they are rapidly worn down and frequently out of round. The building up of these collars to original outside diameters concentric with the pipe bore constitutes what is generally known as drill pipe reconditioning, now practised on a large scale, as an economical manner of avoiding replacement of collars.

Ordinarily, reconditioning is accomplished by similarly reducing or turning down the collars to outside cylindrical surfaces, concentric with the pipe bore, and fixing sleeves on the reduced collars, which sleeves are of substantially the outside diameter. of the collars as originally made and applied to the pipe. Both the box and pin forming collars of each stand of pipe are treated alike with similar sleeves, similarly anchored in place by shrinking the sleeves on the collars, and by welding through openings in the sleeves with, or without, locking elements engaging the sleeves and collars and secured by welding.

It is economically advantageous to avoid welding operations, and it has been found desirable not to rely upon the anchorage formed between reconditioning sleeves and collars by mere shrinkage of heat-expanded sleeves on the collars, especially as to the box forming collars at the upper ends of the stands or pipe sections. While such anchorage may suflice as regards reconditioning sleeves on the pin-forming joint collars, it must be remembered that in going into, and out of, the hole, the elevators used to raise and lower the drill string, engage the lower or inner shoulders of the upper or box forming collars, and thus each of the latter must, in turn, support all of the great weight of that portion of the drill string below the same, which at present includes not only the weight of the bit, but that of long weighty drill collars now commonly employed immediately above the bit.

With the foregoing in mind, it is the primary object of the present invention to provide a method and means whereby a reconditioning sleeve may be applied in such manner that it may, without a welding operation, be prevented from danger of pulling off over the free end of the collar, and whereby it will be so prevented without relying solely upon shrinkage in place, and with but slight deviation from the usual single piece sleeve now generally employed.

The manner and means by which the above is accomplished may be better understood, and more thoroughly appreciated, in the course of the following description in detail thereof, and by reference to the accompanying drawing, which illustrates the best mode so far devised for carrying the invention into practical effect, and forms a part of this specification. In this drawing;

Figure l is a view, partly in elevation and partly in vertical, longitudinal section, of a stand of drill pipe, with its tool joint collars as originally applied thereto.

Figure 2 is a view in elevation of the same after the worn collars have been annularly reduced according to the present invention to receive reconditioning sleeves.

Figure 3 is another view partly in elevation and partly in section, showing the application of reconditioning sleeves in the manner, and according to, the present invention.

Referring now to Figure l of the drawing, there is shown a length or stand of drill pipe Ill, on the upper and lower ends of which tool joint collars H and I 2 are, respectively, fixed. While these collars may be formed integral with the pipe ends, they are here shown as separate parts, pipe threads being indicated at l3 between the pipe ends and the inner end portions of the collars. In

addition to the threaded connection of the collars in this manner, they may be further substantially permanently anchored on the pipe ends by various means, including shrinkage and/or welding operations.

The collars II and I2 are for the purpose of forming tool points between drill pipes or stands III, in the drill string, by means of which the stands are readily joined in going into the hole, and readily disjoined when coming out of the hole. The upper collar II of each stand commonly has internal tool joint threads I4 in its outer end portion, on a taper to mate an externally tool joint threaded pin I5 with which the lower collar is provided. Each of the collars is annularly of an outside diameter substantially greater than the outside diameter of the pipe III in any drill string of externally upset type, a type which is commonly used in rotary drilling operations except where an externally flush drill string is employed by necessity, as for example when drilling under heavy pressure through a blow-out preventer.

Drilling at the high speeds of rotation of the drill string at present, causes rapid wear of the external surfaces of the collars II and I2, not only seriously reducing the thicknesses of the walls threof, but in many instances resulting in outside surfaces eccentric to the bore of the pipe, or in other words, out of round. Reconditioning is then indicated and in the usual operation of this nature the collars II and I2 are further reduced, as by turning the same down, to a smaller outside diameter, as for example to a diameter indicated by the broken lines I6 of Figure 1, sufficientat least to again restore the same to concentricity relative to the pipe bore. The original' diameter is then made up by the application of cylindrical sleeves to the reduced outer surfaces of the collars and their connection thereto, as by means of shrinkage and/or welding operations.

According to the present invention, which seeks among other things to eliminate the necessity for welding operations, the box forming collar II at the upper end of the pipe stand I0, is annularly reduced over its entire surface to a desired point as indicated at I! in Figure 2, and is then further annularly reduced at its inner end portion, at I8, to a diameter smaller than its major 1 portion I'I, sufficient to form between these portions I1 and I8 a downwardly or inwardy facing annular shouder I9.

The lower pin forming collar I2 is then annularly reduced to an outside diameter as indicated at 20 in Figure 2, which is but slightly less than the diameter of the smaller portion I8 of collar II, to thus permit of passage over the re duced collar I2 of a sleeve having a portion presenting an internal diameter to fit upon the smaller portion I8 of collar II.

In Figure 2 there is also indicated by dotted lines II and I2, the approximate outside diameters of the collars II and I2 before reduction in the manner above set forth.

A sleeve such as above mentioned, adapted to be passed lengthwise over the reduced collar I2, is shown at 2| in Figure 3, with a body portion of an internal diameter adapted to be shrunk on the larger reduced main portion I! of collar II, and provided with an annularly, internal flange or ring 22 at its inner end which, after passage in heated, expanded condition over the reduced collar I2, as above, and endwise along pipe I0, is adapted to be shrunk on the smaller reduced portion I8 of collar II, in endwise or longitudinally abutting relation against the annular shoulder I9. 'The sleeve 2I will thus be barred from further movement toward the free end of the collar II, by the abutment of relatively engaging in tegral portions of the collar II and sleeve 2I, so as supplement the shrinking of the sleeve on the collar, to an extent eliminating the necessity of further anchorage, as by means of welding.

Lastly, the pin forming collar I2 is reconditioned by the application of a sleeve 23 thereon, and its connection thereto, as by shrinking thereon. As to this connection, shrinkage is believed suiflcient, since it need not sustain any por tion of the weight of the drill string at any time However, nothing said in this respect is to be taken as precluding the use of further and additional means to fortify this connection if it is desired to do so.

The invention thus eliminates allfiiecessity for welding operations, and the use oyextra fastening elements such as balls and the like ordinarily held in place by welds, and at the same time provides a practical method and means whereby the desired end is accomplished in a highly effective and eflicient manner which assures a ruggedly enduring reconditioned drill pipe, and is in all mechanical respects at least the equal of more expensive welding.

Having thus fully disclosed the invention, what is claimed is: 1. The hereindescribed method of reconditioning a stand of drill pipe, which consists in annularly reducing the upper box forming collar of a pipe stand to form an annular external downwardly facing shoulder intermediate its ends, then reducing the lower pin forming shoulder of the stand to form an outer surface of a diameter less than the diameter of the upper collar at the base of its shoulder, providing a reconditioning sleeve having an internal annular shoulder to abut the shoulder of the upper collar, then passing said sleeve lengthwise over and around the lower re duced collar and onto the upper collar, then shrinking said sleeve on the upper collar with the said shoulders in abutting relation, and finally fixing a reconditioning sleeve on the lower pin forming collar.

2. The hereindescribed method of reconditioning a stand of used drill pipe, which consists in machining the upper box forming collar of a pipe stand to provide a concentric outer face and forming thereon an annular downwardly facing shoulder intermediate the ends thereof, reducing the lower pin forming collar of the stand to an outside diameter less than the diameter of the upper collar at the base of its shoulder, passing an internally, annularly shouldered concentric reconditioning sleeve along and around the reduced lower collar until the shoulder of the sleeve abuts the downwardly facing shoulder machined in said upper box and onto the upper collar, bonding together by heat the, sleeve on the upper collar with the said shoulders in abutting relation, and shrinking a reconditioning sleeve on the lower pin forming collar.

WALTER A. ABEGG. 

